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NQN  CIRCULATING 

CHECK  FOR  UNBOUND 
CIRCULATING  COPY 


UNIVERSITY  OF  ILLINOIS 


Agricultural  Experiment  Station 


BULLETIN  No.  174 


AN  EFFICIENT  AND  PRACTICABLE  METHOD 
FOR  CONTROLLING  MELON  LICE 


BY  C.  E.  DURST 


URBANA,  ILLINOIS,  JULY,  1914 


SUMMARY  OF  BULLETIN  No.  174 

1.  Melon  lice  are  very  difficult  to  combat  successfully  because  of  the  fact 
that  they  live  mainly  on  the  undersurfaces  of  the  leaves,  and  that,  in  order  to 
destroy  them,  their  bodies  must  be  hit  with  a  material  that  kills  by  contact. 

Page  322 

2.  An  attack  by  melon  lice  commonly  begins  on  a  single  hill,  or  on  a  few 
hills  scattered  over   a  patch.     By  timely  treatment   of  the  first  infested  hills, 
combined  with  the  work  of  predaceous  insects,  the  lice  may  often  be  controlled. 
However,  in  seasons  favorable  for  rapid  multiplication,  the  lice  eventually  spread 
over  the  entire  patch  in  spite  of  such  treatment.  Page  322 

3.  The  lice  suck  the  juices  from  the  plant  and  cause  the  leaves  to  curl. 
The  plants  are  weakened,  and  the  crop  is  reduced,  both  in  quality  and  quantity. 
In  the  case  of  severe  attacks,  the  vines  are  often  killed  outright.  Page  322 

4.  Severe  attacks  of  melon  lice  can  be  controlled  by  spraying  with  a  com- 
mercial   preparation   of   nicotine    sulphate    known    as    ' '  Black    Leaf    40. ' '      The 
applications  may  be  made  effectively  with  a  barrel  pump,  equipped  with  lead 
of  hose,  bamboo  rod,  and  nozzle  with  bent  shank  and  fine  cap.  Page  324 

5.  A  solution  of  "Black  Leaf  40"  as  strong  as  one  part  to  250  of  water 
will  not  injure  melon  foliage,  but  a  l-to-500  solution  is  as  effective  against  the 
lice  and  is  recommended  when  particularly  quick  results  are  desired.     A  l-to-1000 
solution  is  practically  as  efficient   and  is   recommended   for   use   in   commercial 
operations.  Page  326 

6.  With  proper  equipment  and  thoro  application,  it  is  possible  to  kill  prac- 
tically every  melon  louse  on  the  vines.     The  material  appears  to  be  so  destructive 
to  the  lice  that  the  finest  mist,  coming  in  contact  with  their  bodies,  is  capable 
of  killing  them.  Page  328 

7.  When  the  vines  are  of  medium  size,  about   200   gallons  of  solution  are 
required  for  spraying  an  acre  of  "rowed"  melons.    Allowing  a  l-to-1000  solution, 
the  "Black  Leaf  40"  for  this  amount  would  cost  $2.50.  Page  330 

8.  Whale-oil  soap  and  tobacco  decoction  are  fairly  efficient  for  controlling 
melon  lice  if  applied  repeatedly,  but  do  not  compare  with  "Black  Leaf  40"  in 
effectiveness  or  in  the  ease  with  which  they  may  be  prepared.  Page  331 

9.  In  the  tests  at  this  station,  fumigation  with  carbon  bisulphide  did  not 
prove  to  be  an  efficient  or  practicable  method  for  controlling  attacks  of  melon 
lice.  Page  332 

10.  Kerosene  emulsion  cannot  be  used  with  safety  for  spraying  muskmelons 
and  cucumbers.  Page  332 

11.  Home-made  lime  sulfur   solution    injures   melon   foliage   when  used   as 
weak  as  1  part  to  40  of   water,   and  does  not  control  the  lice  when  used  as 
strong  as  1  part  to  20  of  water.  Page  333 

12.  RECOMMENDATIONS.  Page  334 


AN  EFFICIENT  AND  PRACTICABLE  METHOD 
FOR  CONTROLLING  MELON  LICE 

BY  C.  E.  DUEST,  ASSOCIATE  IN  OLERICULTURE 

INTRODUCTION 

Muskmelons  have  occupied  a  prominent  place  in  the  vegetable 
tests  of  the  Illinois  Agricultural  Experiment  Station  for  the  last 
twelve  years.  During  that  time  considerable  experience  has  been 
gained  in  combating  the  melon  louse  (Aphis  Gossypii  Glover),  an 
insect  which  is  often  extremely  destructive  to  this  crop,  as  well  as  to 
cucumbers  and  watermelons  and,  in  a  lesser  degree,  to  other  cucur- 
bitaceae.1  The  principal  materials  and  methods  formerly  recom- 
mended for  the  control  of  this  insect  have  been  employed  from  time  to 
time,  but  none  of  them  has  proved  satisfactory  in  the  case  of  a  severe 
attack.  Besides  being  unsatisfactory,  some  of  them  were  found  to  be 
impracticable  for  use  under  certain  conditions  of  vine  growth. 

During  the  season  of  1910,  a  commercial  preparation  of  nicotine 
sulphate,  known  as  "Black  Leaf  40, "2  was  tested  at  the  experimental 
plantation  at  Anna,  Union  county,  Illinois,  and  gave  promising  re- 
sults. Subsequent  tests  have  shown  it  to  be  far  more  efficient  for 
combating  melon  lice  than  any  other  material  with  which  this  station 
has  had  experience.  It  has  further  been  found  that  a  barrel  pump, 
properly  equipped,  may  be  successfully  used  for  the  application  of 
this  material  under  any  field  conditions  which  may  arise,  thus  render- 
ing laborious  hand  methods  unnecessary  and  reducing  the  treatment 
for  serious  attacks  of  this  insect  to  a  practicable  basis. 

The  details  of  these  tests,  together  with  a  resume  of  several  other 
methods  and  materials  tested  on  various  occasions,  are  presented  in 
the  following  pages. 


1  Other  plants  infested  by  this  aphis  (Chittenden,  F.  H.,  U.  S.  Bur.  Ent.  Cir. 
80,  November,  1906)  are  cotton,  okra,  orange  and  other  citrus  fruits,  strawberry, 
purslane,  clover,  bean,  beet,  spinach,  tomato,  hop,  pear,  and  a  number  of  orna- 
mental plants  and  common  weeds. 

2 ' '  Black  Leaf  40 "  is  a  concentrated  solution  of  nicotine  sulphate  containing 
40  percent  of  nicotine,  manufactured  by  the  Kentucky  Tobacco  Product  Company, 
Louisville,  Kentucky. 

321 


322  BULLETIN  No.  174  [July, 

HABITS  AND  NATURE  OF  ATTACK  OF  THE  MELON 

LOUSE 

The  melon  louse  obtains  its  subsistence  by  sucking  the  juices  from 
the  host  plant,  drawing  them  out  by  means  of  its  beak,  which  it  in- 
serts in  the  tissues.  It  has  a  tender  body  and  cannot  withstand  ex- 
posure to  direct  sunlight ;  hence  it  lives  mainly  on  the  undersurf aces 
of  the  leaves.  The  insect  may,  however,  attack  the  upper  surfaces 
with  equal  severity  when  those  parts  are  shaded. 

An  attack  of  melon  lice  commonly  begins  on  a  single  hill,  or  on 
a  few  hills  scattered  over  a  patch.  Occasionally,  infestation  is  more 
or  less  general  from  the  start.  Sometimes  the  attack  begins  while  the 
plants  are  yet  small,  but  more  often  about  the  time  the  weather  is 
becoming  warm  and  the  vines  have  begun  to  run.  Occasionally,  how- 
ever, the  attack  does  not  become  severe  until  comparatively  late  in  the 
season;  for  instance,  in  1912  the  lice  did  not  become  abundant  in 
Union  county  until  the  latter  part  of  August,  when  the  picking  sea- 
son was  drawing  to  a  close. 

The  extraction  of  vital  juices  from  the  plants  weakens  them,  and 
the  crop  is  reduced  both  in  quantity  and  quality.  The  first  visible 
effect  is  a  curling  downward  of  the  edges  of  the  leaves.  When  an 
attack  is  allowed  to  proceed  unchecked,  a  condition  is  soon  reached 
like  that  shown  in  Fig.  1.  The  insects  multiply  with  great  rapidity 
under  favorable  weather  conditions,  and  often  within  a  week  or  ten 
days  after  the  first  notice  of  infestation  they  have  spread  over  a  large 
area  and  caused  irreparable  damage.  In  the  case  of  a  severe  attack, 
especially  in  dry  weather,  the  plants  may  be  killed  outright. 

Because  of  its  habit  of  obtaining  food  by  sucking  the  juices  of 
the  plant,  the  melon  louse  is  not  affected  in  the  least  by  the  poisonous 
substances  that  would  be  quickly  fatal  to  chewing  insects.  The  most 
practicable  method  of  combating  it  is  to  bring  into  touch  with  its 
body  some  material  that  is  capable  of  killing  by  contact.  The  tender 
body  of  the  insect  renders  it  readily  susceptible  to  such  treatment. 
The  material  used,  besides  being  capable  of  destroying  the  insect, 
must  be  one  that  will  not  injure  the  foliage.  These  circumstances, 
combined  with  the  fact  that  the  insect  lives  chiefly  on  the  undersur- 
faces  of  the  leaves,  which  are  not  easily  reached  with  a  spray,  make 
it  a  most  difficult  matter  to  combat  a  severe  attack  successfully. 

It  is  a  practice  of  many  growers  to  watch  closely  for  the  first 
infested  hills,  and  to  treat  the  lice  there  as  soon  as  discovered.  The 
chief  methods  of  doing  this  are  by  burying  the  infested  vines,  by  burn- 
ing straw  over  the  hills,  by  spraying  thoroly  with  a  contact  insecticide, 
or  by  dusting  the  plants  with  fine  tobacco  powder  or  pyrethrum. 
These  practices,  coupled  with  the  work  of  the  ladybird  beetles  (Coc- 


1914} 


CONTROLLING  MELON  LICE 


323 


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02 

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324  BULLETIN  No.  174  [July, 

cinellidas),1  which,  are  the  chief  predaceous  insect  enemies  of  the 
melon  louse,  often  suffice  to  control  an  attack  and  are  certainly  to  be 
recommended.  However,  it  is  a  matter  of  experience  reported  by 
practical  growers,  and  it  has  been  observed  at  this  station,  that  in  a 
season  favorable  for  rapid  multiplication  of  the  lice,  they  eventually 
spread  over  the  patch  in  spite  of  all  precautionary  single-hill  treat- 
ments and  the  work  of  the  ladybird  beetles  combined. 


SPRAYING  WITH  "BLACK  LEAF  40" 
TESTS  IN  1910  AND  1911 

"Black  Leaf  40"  was  tested  by  this  station  for  the  first  time  at 
Anna,  Union  county,  in  1910.  Other  methods  of  combating  the  lice 
on  individual  hills  having  been  employed  with  indifferent  success, 
solutions  of  this  material  were  applied  to  infested  plants  by  means  of 
an  atomizer.  As  is  usual  in  handling  this  apparatus,  it  was  necessary 
for  one  person  to  turn  the  vines  while  another  directed  the  spray. 
Two  strengths  of  material  were  used:  1  part  in  250  parts  of  water, 
and  1  part  in  500  of  water.  Both  solutions  were  noticeably  effective 
against  the  lice  and  did  not  injure  the  foliage.  Altho  this  treatment 
served  to  hold  the  insects  in  check,  it  was  impossible,  on  account  of 
the  inadequacy  of  the  equipment  used,  to  exterminate  them  as  thoroly 
as  was  desired.  The  material  gave  such  satisfactory  results,  however, 
that  it  was  decided  to  give  it  further  trial  another  season. 

In  1911  the  lice  appeared  at  Anna  early  in  the  season  on  a  num- 
ber of  hills  scattered  at  intervals  over  the  patch.  Such  hills,  as  soon 
as  discovered,  were  buried  if  found  badly  infested,  and  if  only  moder- 
ately so,  were  sprayed  with  "Black  Leaf  40,"  1  part  to  250  parts  of 
water.  An  atomizer  was  again  used  for  making  the  application.  These 
methods,  combined  with  the  work  of  the  ladybird  beetles,  which  were 
fairly  abundant,  sufficed  to  hold  the  lice  in  control  for  a  time.  How- 
ever, on  July  10  they  were  found  scattered  over  the  entire  melon 
plantation.  The  weather  was  warm  and  the  soil  was  fairly  moist.2 
The  vines  were  growing  rapidly  and  were  full  of  sap.  Under  these 
conditions  the  lice  multiplied  very  rapidly,  and  it  was  apparent  that 


1  There  are  several  species  of  this  family,  nearly  all  of  which  eat  melon  lice. 

2  From  July  1  to  10  the  maximum  and  minimum  temperatures  were  as  follows : 

Max.     Min.  Max.  Miti. 

July  1 102.5        66  July  6 95        75 

July  2 102          68  July  7 98       72 

Jnly3 106  74  July  8 92       73.5 

July  4 106.5       76  July  9        94       74 

JulyS 99          76  July  10 98       74 

There  was  a  rain  of  0.38  inch  June  24  and  a  light  shower  July  4. 


1914] 


CONTROLLING  MELON  LICE 


325 


more  heroic  and  practicable  methods  than  the  single-hill  treatments 
would  have  to  be  employed  if  the  melons  were  to  be  saved.  Accord- 
ingly, on  July  13  a  barrel  pump  was  rigged  out  with  a  lead  of  hose, 
bamboo  rod,  and  single  vermorel  nozzle  with  bent  shank  and  fine  cap ; 
and  the  entire  plantation  was  sprayed  with  "Black  Leaf  40,"  1  part 
to  300  of  water.1  The  spraying  outfit  was  drawn  thru  the  patch  on  a 
stone  boat.  In  applying  the  spray,  high  pressure  was  used  and  the 
nozzle  was  worked  under  and  between  the  leaves  so  as  to  cover  the 
vines  as  thoroly  as  possible.  The  vines  had  been  "rowed"2  for  cul- 


FIG.  2. — MELON  VINES  WHICH  HAVE  BEEN   "BOWED"  FOR  CULTIVATION  ARE  MORE 
EASILY  TREATED  FOR  LICE 

tivation,  as  shown  in  Fig.  2,  so  that  it  was  not  so  difficult  to  do  this  as 
would  have  been  the  case  if  no  training  had  been  done.3 

The  day  after  the  spraying,  scarcely  a  live  louse  could  be  found. 
Even  on  the  leaves  so  situated  that  it  seemed  unreasonable  to  suppose 
that  the  spray  had  reached  the  lice,  a  diligent  search  was  required  to 
find  any  surviving  insects.  Coincident  with  the  death  of  the  lice,  the 
large  black  ants  which  had  accompanied  them  also  disappeared 


1  The  preparation  of  this  solution  is  very  simple,  it  being  only  necessary  to 
measure  out  the  desired  amount  of  the  material  and  mix  it  with  the  water. 

2 ' '  Eowing ' '  consists  simply  in  turning  the  vines  during  the  growing  season, 
so  that  they  will  run  in  the  direction  of  the  rows.  Two  or  three  trainings  are 
necessary  during  a  season  to  keep  the  vines  within  bounds. 

a  At  the  time  the  spraying  was  done,  the  vines  from  adjacent  hills  had  become 
well  entangled  and  the  first  fruits  were  ripening. 


326  BULLETIN  No.  174  [July, 

The  spray  proved  so  effective  against  the  lice  that  it  was  decided 
to  submit  it  to  further  tests  as  soon  as  opportunity  afforded,  and 
among  other  things,  to  determine  the  most  desirable  strength  to  use ; 
but  the  lice  did  not  appear  again  at  Anna  during  the  season  in  suffi- 
cient numbers  to  permit  such  tests. 

At  Urbana  in  1911,  the  same  results  were  secured  as  at  Anna. 
The  lice  became  very  abundant  during  the  latter  part  of  August,  at 
which  time  some  of  the  melons  were  ripening.  The  area  devoted  to 
melons  was  not  large  enough  to  test  adequately  different  strengths  of 
the  material ;  so  all  the  vines  were  sprayed  with  a  solution  containing 
1  part  of  "Black  Leaf  40"  in  300  of  water,  the  applications  being 
made  in  the  same  way  as  at  Anna.  Examination  two  days  after  spray- 
ing showed  practically  all  the  lice  to  be  dead,  and  the  insects  did  not 
reappear  in  sufficient  numbers  to  be  of  any  consequence. 

TESTS  IN  1912 

At  Anna  in  1912  lice  appeared  during  early  July  on  a  number  of 
hills  scattered  over  the  area  devoted  to  melons,  but  disappeared  for 
the  time  being.1  A  period  of  cool  weather  began  July  17  and  con- 
tinued almost  unbroken  until  August  15.  It  appeared  that  this  cool 
weather  prevented  the  lice  from  multiplying  rapidly,  so  that  the  lady- 
bird beetles,  which  were  fairly  numerous,  were  able  to  take  care  of 
them.  With  the  return  of  warm  weather,  however,  the  lice  reappeared 
and  soon  were  found  to  be  very  abundant. 

At  this  time  the  picking  season  was  nearing  its  close,  and  while 
it  was  unnecessary  to  treat  the  lice  so  far  as  the  crop  was  concerned, 
it  was  decided  to  take  advantage  of  the  opportunity  to  make  a  test  of 
various  strengths  of  "Black  Leaf  40."  In  fact,  it  seemed  an  ideal 
time  for  putting  the  material  to  a  rigid  test,  for  the  vines  had  at- 
tained their  full  growth,  and  the  leaves  were  more  or  less  worn  with 
age.  These  circumstances  combined  to  make  the  foliage,  especially 
near  the  middle  of  the  rows,  less  accessible  to  a  spray  than  is  ordina- 
rily the  case  at  the  time  treatment  for  lice  is  necessary.  As  a  whole, 
the  vines  and  foliage  were  yet  in  very  excellent  condition,  considering 
their  age. 

On  August  21  plats  of  equal  size  were  sprayed  with  different 
strengths  of  ' '  Black  Leaf  40, ' '  as  follows : 

1  part  in  300  of  water 

1  part  in  500  of  water 

1  part  in  600  of  water 

1  part  in  800  of  water 

1  part  in  1000  of  water 

The  applications  were  made  between  1  and  3  p.  m.,  with  the  same 
equipment  and  in  the  same  manner  as  in  1911.     During  the  night 


1  No  attempt  had  been  made  to  combat  the  lice  on  individual  hills. 


1914]  CONTROLLING  MELON  LICE  327 

following  the  application,  there  was  a  dashing  rain  amounting  to  0.8 
inch. 

Examination  on  August  23,  two  days  after  the  spraying,  showed 
the  following  results :  The  l-to-300,  l-to-500,  and  l-to-600  solutions  of 
"Black  Leaf  40"  appeared  to  be  equally  effective  in  destroying  the 
lice.  None  of  these  strengths  injured  the  foliage,  and  all  of  them 
killed  practically  every  insect  on  the  plants,  even  on  the  leaves  so 
curled  or  so  situated  in  the  centers  of  the  hills  that  the  lice  on  them 
were  apparently  out  of  reach  of  the  spray.  The  l-to-700  and  weaker 
solutions  seemed  to  have  left  more  lice  on  the  foliage  not  well  exposed, 
varying  with  the  weakness  of  the  solution.  In  no  case,  however,  did 
it  appear  that  enough  of  the  insects  had  escaped  to  cause  a  serious 
infestation  within  a  reasonable  length  of  time.  On  well-exposed 
leaves,  the  lice  were  as  effectually  destroyed  by  the  weaker  solutions 
as  by  any. 

Further  examination  of  the  sprayed  plats  on  August  27  and  30 
showed  that  the  weaker  solutions  had  controlled  the  insects  much  bet- 
ter than  was  apparent  at  the  time  of  the  first  examination.  Not 
enough  lice  could  be  found,  even  on  the  plat  sprayed  with  1  part 
' '  Black  Leaf  40  "  in  1000  parts  of  water,  to  be  of  any  practical  signifi- 
cance. No  harm  had  resulted  to  the  foliage  from  the  use  of  even  the 
strongest  solutions.  Examinations  of  unsprayed  plants  at  the  same 
time  showed  a  great  number  of  lice  present  and  many  leaves  curled 
as  a  result. 

In  order  to  make  further  tests  of  the  strength  of  "Black  Leaf 
40 ' '  required,  another  set  of  plats,  which  had  not  been  treated  before, 
was  sprayed  on  August  27.  The  applications  were  made  between  1 
and  3  p.  m.  The  day  was  bright  and  warm.  Many  melon  leaves  were 
much  curled  at  this  time  from  the  effects  of  the  lice.  The  strengths 
of  "Black  Leaf  40"  used  were  as  follows: 

1  part  in  400  of  water 

1  part  in  600  of  water 

1  part  in  800  of  water 

1  part  in  1000  of  water 

1  part  in  1200  of  water 

Examination  on  the  following  day  showed  that  practically  all 
the  lice  were  dead  on  the  plat  sprayed  with  the  l-to-400  solution. 
There  seemed  to  be  a  few  more  lice  left  by  each  succeeding  weaker 
solution,  but  the  differences  were  so  slight  as  to  be  scarcely  recogniz- 
able on  contiguous  plats;  it  was  necessary  to  go  from  one  of  the 
weaker  to  one  of  the  stronger  solutions  to  observe  a  noticeable  differ- 
ence. The  l-to-1000  strength  of  "Black  Leaf  40"  had  killed  nearly 
all  the  insects,  and  gave  every  indication  of  being  sufficiently  strong 
to  control  the  situation  well  enough  to  warrant  recommending  its  use 
in  commercial  practice.  The  l-to-1200  solution  at  this  time  appeared 
to  have  left  too  many  of  the  insects,  especially  on  leaves  not  well  ex- 


328  BULLETIN  No.  174  [July, 

posed,  to  warrant  advising  its  use.  Further  examination  on  August 
30  showed  very  few  lice  on  any  of  the  plats.  Apparently,  many  of 
the  insects  which  were  alive  at  the  time  of  the  previous  examination 
had  succumbed  during  the  three-day  interval.  So  few  lice  were  found 
at  this  time  on  the  plat  sprayed  with  the  l-to-1200  solution  that  this 
strength  appeared  capable  of  controlling  them.  As  in  the  previous 
test,  no  foliage  injury  had  resulted  from  the  use  of  any  of  the  solu- 
tions. On  unsprayed  plants,  the  lice  continued  to  be  abundant  and 
had  caused  serious  damage. 

SUMMARY  OF  TESTS  WITH  "BLACK  LEAF  40" 

To  summarize  the  results  of  the  tests  with  various  strengths  of 
' '  Black  Leaf  40, ' '  it  may  be  stated  that  a  solution  as  strong  as  1  part 
of  the  material  to  250  of  water  may  be  used  without  injury  to  melon 
foliage.  One  part  to  500  or  600  of  water  is  as  effective  against  the 
lice  and  is  recommended  for  use  when  particularly  quick  results  are 
desired.  A  solution  containing  1  part  of  the  material  to  1000  of 
water  is  somewhat  slower  in  action,  but  from  a  practical  viewpoint 
will  prove  as  effective  as  a  stronger  solution.  In  the  tests  from  which 
these  conclusions  are  drawn,  a  l-to-1000  solution  destroyed  practically 
all  the  lice  each  time  it  was  used,  and  gave  every  indication  of  being 
capable  of  controlling  serious  attacks  of  the  insects  well  enough  to 
warrant  recommending  its  use  in  commercial  practice.  In  view  of 
only  the  one  test  made  with  a  solution  weaker  than  1  part  to  1000 
of  water,  even  tho  apparently  successful,  it  is  not  considered  feasible 
to  advise  a  weaker  solution.  It  is  possible,  however,  that  further  tests 
may  prove  a  weaker  solution  to  be  capable  of  controlling  the  lice  sat- 
isfactorily. 

METHOD  OF  APPLICATION 

While  the  material  itself  and  its  proper  dilution  are  highly  im- 
portant matters  in  successfully  combating  melon  lice,  they  are  not 
more  important  than  the  method  of  application. 

In  the  first  place,  the  "Black  Leaf  40"  solution  must  come  into 
direct  contact  with  the  insects  if  they  are  to  be  destroyed.  When 
this  material  was  first  applied  with  the  barrel  outfit  in  1911,  it  was 
thought,  in  view  of  the  extremely  satisfactory  results  obtained,  that 
possibly  it  killed  by  its  fumes,  or  in  some  other  way  than  by  coming 
into  direct  contact  with  the  insects  at  the  time  of  application.  It  was 
not  supposed  that  the  spray  had  reached  the  undersurfaces  of  many 
of  the  leaves  lying  close  to  the  ground  or  near  the  center  of  the  hills, 
yet  the  lice  were  killed  on  practically  every  leaf  of  the  plants.  To 
make  a  test  of  this  point,  a  plat  was  sprayed  in  1912,  at  Anna,  merely 
over  the  tops  of  the  vines  with  a  l-to-300  solution  of  "Black  Leaf  40." 


1014] 


CONTROLLING  MELON  LICE 


329 


This  treatment  did  not  kill  the  lice,  except  on  well-exposed  leaves, 
while  on  other  plats  sprayed  under  the  leaves  at  the  same  time,  they 
were  killed.  Evidently  this  material  must  come  into  direct  contact 
with  the  insects  if  it  is  to  destroy  them. 

The  above  circumstance  suggests  that  the  spray,  when  properly 
applied,  reaches  more  of  the  vine  than  would  ordinarily  be  supposed. 


FIG.  3. — NEAR  VIEW  OF  THE  UNDERSURFACE  OF  A  MELON  LEAF  BADLY  INFESTED 

WITH  LICE 

In  1912  the  plants  were  closely  examined  on  several  occasions  after 
applying  the  spray,  and  it  was  found  that  the  material  had  actually 
reached  the  undersurfaces  of  practically  every  leaf,  tho  in  many  cases 
it  was  present  only  in  very  fine  particles  scattered  over  the  surface, 
such  as  would  be  deposited  from  a  mist.  When  the  method  of  appli- 


330  BULLETIN  No.  174  [July, 

cation  is  taken  into  account,  it  is  not  difficult  to  understand  why  this 
should  be  the  case.  The  vermorel  nozzle,  which  was  used  in  these 
tests,  throws  an  especially  fine  spray  near  the  nozzle  opening.  With 
the  very  fine  cap,  the  bent  shank,  the  high  pressure,  and  the  care 
taken  in  applying  the  material,  it  may  be  readily  understood  why  it 
was  possible  to  reach  the  undersurfaces  of  practically  every  leaf  on 
the  plants. 

Many  melon  growers  have  been  of  the  opinion  that  it  is  not  feas- 
ible to  control  a  serious  attack  of  lice  because  of  the  impracticability 
of  reaching  the  insects  with  the  spray,  but  in  view  of  the  results  ob- 
tained at  this  station  with  '  '  Black  Leaf  40,  '  '  it  appears  that  the  diffi- 
culty had  been  due  to  ineffectiveness  on  the  part  of  the  materials  used 
rather  than  to  the  impossibility  of  thoro  application.  With  the  proper 
equipment  and  the  exercise  of  care  in  applying  the  spray,  it  is  pos- 
sible, without  very  much  trouble,  to  reach  practically  every  part  of 
the  plants.  "Black  Leaf  40"  is  apparently  so  destructive  to  the  lice 
that  the  finest  mist  made  by  the  nozzle,  coming  in  contact  with  their 
bodies,  is  capable  of  killing  them. 

AMOUNT  OF  MATERIAL  KEQUIRED 

In  order  to  determine  how  much  "Black  Leaf  40"  would  be  re- 
quired to  spray  a  given  area,  an  observation  was  made  at  Anna  on 
August  27,  1912,  regarding  the  amount  of  liquid  needed  to  spray  an 
area  amounting  to  one-eleventh  of  an  acre.  The  application  was 
made  with  the  same  equipment  and  in  the  same  manner  as  that  pre- 
viously described.  Eighteen  gallons  of  solution  were  required  to  cover 
the  vines  properly.  This  is  at  the  rate  of  198,  or  practically  200,  gal- 
lons per  acre.1 

The  vines  sprayed  in  this  test  had  attained  only  a  moderate  size 
during  the  season,  and  more  material  would  undoubtedly  be  required 
when  growth  is  heavy.  Also,  on  account  of  the  vines  being  '  '  rowed,  '  ' 
less  material  was  necessary  than  would  otherwise  have  been  the  case. 
On  the  other  hand,  it  should  be  remembered  that  these  vines  had  at- 
tained their  full  seasonal  growth,  and  that  for  spraying  early  in  the 
season,  when  the  vines  are  not  fully  developed,  less  material  would 
be  required. 

COST  OF  SPRAYING  WITH  "BLACK  LEAF  40" 

"Black  Leaf  40"  is  sold  in  cans  of  various  sizes,  at  the  prices 
indicated  below: 


pounds   ........................................  $12.50 

2%  pounds   ........................................     3.25 

i/z    pound  ...........................................  85 

The  material  has  a  specific  gravity  of  1.20  to  1.24,  varying  some- 

1  Incidentally,  it  may  be  said  that  a  l-to-500  solution  was  used,  and  that  the 
lice  were  effectually  destroyed. 


1914}  CONTROLLING  MELON  LICE  331 

what  with  the  amount  of  inert  substances  present.  A  gallon  usually 
weighs  a  little  more  than  ten  pounds.  Thus,  it  will  be  seen  that  the 
10%-pound  can  contains  approximately  one  gallon  of  material.  There- 
fore, allowing  for  a  l-to-1000  solution  and  using  200  gallons  per  acre, 
the  material  required  for  spraying  an  acre  of  melons  for  melon  lice 
would  cost  $2.50.  The  expense  will  vary  from  this,  of  course,  with 
the  size  of  the  vines  and  the  method  of  training,  but  it  is  safe  to  regard 
this  amount  as  being  somewhere  near  the  correct  figure. 

TEST  OF  OTHER  MATERIALS 

As  stated  in  the  introduction,  other  materials  besides  "Black 
Leaf  40"  have  been  tested  from  time  to  time.  Whale-oil  soap  was 
employed  on  various  occasions  previous  to  the  season  of  1909.  Fumi- 
gation with  carbon  bisulphide  was  given  a  thoro  trial  in  1909.  Lime- 
sulfur  solution  was  tested  in  1912.  Kerosene  emulsion  and  tobacco 
decoction,  while  not  used  by  the  Station  for  combating  melon  lice, 
have  been  used  by  the  author  in  commercial  work.  A  brief  account 
of  the  facts  revealed  in  the  tests  with  these  materials  is  presented  in 
the  following  pages. 

WHALE-OIL  SOAP  SOLUTION 

Whale-oil  soap  has  been  employed  on  a  number  of  occasions  at 
this  station  for  combating  melon  lice,  dating  back  to  1901,  but  it  has 
never  proved  more  than  partially  effective  in  controlling  them.  Two 
strengths  of  solution  have  been  used ;  1  pound  of  the  soap  to  8  gallons 
of  water,  and  1  pound  to  6  gallons  of  water.  The  former  strength  has 
been  found  only  fairly  satisfactory.  It  was  always  necessary  when 
there  was  a  severe  attack  of  the  lice  to  apply  the  spray  repeatedly  to 
hold  them  in  check.  The  stronger  solution  was  found  somewhat  more 
effective,  but  injured  melon  and  cucumber  foliage  under  some  weather 
conditions. 

In  addition  to  being  only  fairly  efficient,  whale-oil  soap  solution 
is  not  easily  prepared.  The  quickest  way  to  make  the  solution  is  to 
cut  the  soap  into  thin  slices  and  dissolve  it  in  boiling  water,  'at  the 
rate  of  about  a  pound  to  a  gallon  of  water.  This  is  what  is  called  a 
stock  solution,  and  may  be  prepared  in  advance.  When  it  is  desired 
to  make  the  application,  this  stock  solution  is  diluted  with  the  quan- 
tity of  water  necessary  to  make  a  solution  of  the  desired  strength. 
Thus,  it  will  be  seen  that  the  preparation  of  whale-oil  soap  solution  is 
not  a  small  task.  Incidentally,  it  is  also  a  somewhat  disagreeable  task, 
at  least  to  some  persons,  on  account  of  the  unpleasant  odor  of  the  soap. 
Compared  with  "Black  Leaf  40,"  whale-oil  soap  is  not  only  much 
less  easily  prepared,  but  it  is  far  less  effective  in  controlling  the  lice. 


332  BULLETIN  No.  174 

FUMIGATION  WITH  CARBON  BISULPHIDE 

Considerable  has  been  written  during  recent  years  in  regard  to 
fumigating  individual  plants  for  lice  with  poisonous  gases.  The  ma- 
terials commonly  suggested  for  this  purpose  are  carbon  bisulphide, 
hydrocyanic  acid  gas,  and  various  tobacco  preparations. 

Tests  with  carbon  bisulphide  for  the  control  of  melon  lice  were 
conducted  at  Anna  during  the  season  of  1909.  The  literature  on  the 
subject  was  first  reviewed  fully,  and  in  making  the  tests  the  recom- 
mended amounts,  and  also  larger  and  smaller  amounts,  were  used. 
Each  amount  was  used  for  the  recommended  length  of  time  and  also 
foi  longer  and  shorter  periods.  For  covering  the  plants,  butter  tubs 
were  used.  In  all  cases  where  any  appreciable  number  of  the  lice 
were  killed,  the  plants  were  more  or  less  injured.  In  every  case 
where  the  plants  survived  the  treatment,  many  of  the  insects  also 
survived. 

Besides  proving  inefficient,  several  practical  difficulties  were  en- 
countered during  the  course  of  the  tests  which  showed  fumigation 
methods  to  be  impracticable  for  use  under  some  conditions  which  pre- 
sent themselves  in  a  melon  patch.  The  plants  may  be  covered  readily 
while  small,  but  after  they  have  begun  to  spread,  the  vines  must  be 
handled  more  or  less  roughly  to  bring  them  within  the  limits  of  the 
covers,  which  operation  is  always  attended  with  more  or  less  damage. 
Furthermore,  it  is  often  found  necessary  to  treat  melon  and  cucumber 
vines  for  lice  after  they  have  reached  full  size.  Covering  under  such 
conditions  is  altogether  impracticable.  In  addition  to  this  difficulty, 
fumigation  was  found  to  be  a  slow  and  tedious  process  in  the  field. 
Another  minor  objection  is  that  the  fumes  of  carbon  bisulphide  are 
somewhat  poisonous  and  very  inflammable.  The  operator  must  not 
smoke  while  using  carbon  bisulphide.  From  the  tests  made,  it  was 
concluded  that  fumigation  with  carbon  bisulphide  is  not  an  efficient  or 
practicable  method  for  controlling  melon  lice.1 

TOBACCO  DECOCTION  AND  KEROSENE  EMULSION 

These  two  materials,  while  not  tested  by  the  Experiment  Station 
for  controlling  lice  on  melons  or  cucumbers,  have  been  used  by  the 
writer  in  commercial  work.  Tobacco  decoction,  made  by  boiling  vari- 


1  Hydrocyanic  acid  gas,  while  not  used  by  this  station  for  combating  melon 
lice,  would  undoubtedly  meet  with  the  same  practical  disadvantages,  and  in  addi- 
tion would  be  particularly  objectionable  because  of  its  extremely  deadly  nature. 
Fumigation  tests  with  various  tobacco  extracts,  prepared  papers,  and  tobacco 
smoke  have  been  reported  from  several  sources  as  giving  satisfaction.  While 
these  materials  may  undoubtedly  be  employed  with  greater  personal  safety  and 
less  danger  of  injury  to  foliage  than  carbon  bisulphide  or  hydrocyanic  acid  gas, 
their  use  is  without  a  doubt  beset  by  the  same  practical  disadvantages. 


1914]  CONTROLLING  MELON  LICE  333 

ous  tobacco  materials  in  water,  was  found  to  be  fairly  effective,  but 
it  had  to  be  applied  repeatedly  in  order  to  hold  the  lice  in  check.  It 
appeared  to  be  somewhat  more  efficient  than  whale-oil  soap  solution 
for  controlling  the  insects,  but  the  results  obtained  from  its  use  have 
no  comparison  with  those  derived  at  this  station  from  the  use  of  ' '  Black 
Leaf  40."  Besides  being  incapable  of  holding  severe  attacks  of  the 
lice  in  check  without  repeated  application,  tobacco  decoction  is  incon- 
venient to  make,  and  its  strength  is  always  more  or  less  uncertain 
because  of  the  variation  in  the  strength  of  tobacco  materials  used  in 
its  preparation. 

Kerosene  emulsion  was  used  on  several  occasions,  but  at  no  time 
did  it  prove  satisfactory  for  treating  melon  lice.  It  invariably  pro- 
duced serious  injury  to  the  foliage,  even  when  prepared  with  the  most 
extreme  care  and  according  to  the  most  approved  directions.  In  fact, 
it  seems  impossible,  under  practical  conditions,  to  so  make  this  mate- 
rial that  it  will  not  injure  melon  foliage.  In  the  opinion  of  the 
author,  kerosene  emulsion  is  altogether  unsuited  for  spraying  tender- 
foliaged  plants  like  muskmelons  and  cucumbers,  and  should  be  omitted 
from  the  many  spray  calendars  where  it  now  occurs  recommended  for 
that  purpose. 

LIME-SULFUR  SOLUTION 

Lime-sulfur  solution  has  given  such  universal  satisfaction  as  a 
contact  insecticide  in  combating  scale  insects  that  it  was  thought  that 
possibly  a  weak  solution  of  the  material,  such  as  is  used  for  the  sum- 
mer spraying  of  fruits,  might  be  used  with  effect  in  controlling  melon 
lice.  In  order  to  make  a  test  of  its  qualities  for  this  purpose,  several 
plats  of  muskmelons  were  sprayed  at  Anna,  in  1912,  with  different 
strengths  of  solution.  Home-made  lime  sulfur  was  used,  each  gallon 
of  concentrated  material  containing  iy2  pounds  of  sulfur.  On  August 
26  plats  of  equal  size  were  sprayed  with  the  following  strengths  of 

solution : 

1  part  in  20  parts  of  water 
1  part  in  25  parts  of  water 
1  part  in  30  parts  of  water 
1  part  in  35  parts  of  water 
1  part  in  40  parts  of  water 

The  same  equipment  and  the  same  method  of  application  were  em- 
ployed as  are  described  in  connection  with  the  tests  with  ' '  Black  Leaf 
40."  The  applications  were  made  between  1  and  3  p.  m.,  and  the 
day  was  bright  and  warm,  as  was  the  case  with  most  of  the  tests  with 
the  above  material. 

Examination  on  August  27,  the  day  following  the  applications, 
showed  that  fully  one-third  of  the  lice  were  still  alive  on  the  plat 
sprayed  with  the  l-to-20  solution,  and  that  on  all  the  plats  the  foliage 
had  been  badly  injured,  the  stronger  solutions  causing  the  greatest 


33 •«.  BULLETIN  No.  174  [July, 

damage.  In  view  of  these  tests,  it  was  concluded  that  lime-sulfur 
solution,  at  least  in  the  strengths  used,  cannot  be  employed  with 
safety  for  spraying  muskmelons,  and  that  even  tho  it  could,  it  would 
not  be  an  efficient  material  for  controlling  melon  lice. 

RE  COMMENDATIONS 

This  experiment  station  has  had  more  or  less  experience  in  com- 
bating melon  lice  for  the  past  twelve  years.  During  that  time  a  num- 
ber of  the  more  important  materials  recommended  for  the  control  of 
this  insect  have  been  used,  but  none  of  them  has  given  as  satisfactory 
results  as  a  commercial  preparation  of  nicotine  sulphate,  known  as 
"Black  Leaf  40,"  which  has  been  thoroly  tested  for  three  seasons. 

This  material  will  not  injure  the  melon  foliage  when  used  as 
strong  as  1  part  to  250  of  water.  One  part  to  500  or  600  of  water  is 
to  all  appearances  as  effective,  and  should  be  used  when  particularly 
quick  results  are  desired.  One  part  to  1000  of  water  will  prove  prac- 
tically as  effective,  and  is  recommended  for  use  in  commercial  prac- 
tice. 

In  the  tests  from  which  these  conclusions  are  drawn,  a  barrel 
pump,  equipped  with  lead  of  hose,  bamboo  rod,  and  nozzle  with  bent 
shank  and  fine  cap  was  successfully  used  for  making  the  applications. 
Any  outfit  capable  of  throwing  a  fine  spray  with  reasonable  force  may 
be  used  with  equal  success. 

The  type  of  nozzle  used  is  an  important  matter  in  treating  melon 
lice.  It  should  have  a  bent  shank  so  that  the  undersurfaces  of  the 
leaves  may  be  reached;  and  it  should  have  a  fine  cap  in  order  that 
the  material  may  be  distributed  as  a  very  fine  mist.  A  single  vermorel 
nozzle  will  be  found  better  adapted  to  this  purpose  than  some  other 
nozzles  for  the  reason  that  it  throws  a  finer  mist  near  the  opening. 

In  applying  the  spray,  high  pressure  should  be  used  and  the 
nozzle  should  be  carefully  moved  about  under  and  between  the  leaves. 
With  due  care  in  Handling  the  nozzle,  it  is  possible  to  reach  the  un- 
dersurfaces of  practically  every  leaf  on  the  plants.  ' '  Black  Leaf  40 ' ' 
solution  is  apparently  so  destructive  to  the  lice  that  the  finest  mist, 
coming  in  contact  with  their  bodies,  is  capable  of  killing  them. 

It  will  be  found  easiest  to  apply  the  spray  to  melon  and  cucumber 
vines  that  have  been  "rowed."  This  operation  consists  simply  in 
turning  the  shoots  during  the  growing  season  so  that  they  will  run  in 
the  direction  of  the  rows,  and,  as  described  in  a  previous  publication1 
of  this  station,  is  highly  advisable  for  purposes  of  weed  killing  and 
moisture  retention.  It  is  feasible,  however,  to  treat  melon  vines  for 
lice  that  have  not  been  "rowed,"  tho  more  time  and  material  would 
be  required. 

1  Circular  No.  139 


UNIVERSITY  OF  ILLINOIS-URBANA 

Q  630.7IL6B  C001 

BULLETIN.  URBANA 
166-181  1914-15 


30112019528436 


W: 


^« 


